Inertia element operated device



April 1941- H. M. SALMOND ETAL 2,236,959

INERTIA ELEM-EMT OPERATED DEVICE Filed Ji 20, 1959 3 Sheets-813st 1 Fig. I. 17

Fig. 2.

f 1 Q I in I Inventor;

April 1941- H. M. SALMOND ETAL 2,236,959

INERTIA ELEMENT OPERATED DEVICE Filed June 20, 1939 3 Sheets-Sheet 2 lnvenlur April 1, 1941- H. M. SALMOND ETAL INERTIA ELEMENT OPERATED DEVICE Filed June 20, 19159 3 Sheets-Sheet 3 Inventor y yfi a ittomcg M g y B Patented Apr. 1, 1941 UNITED STATES PATENT OFFICE INERTIA ELEMENT OPERATED DEVICE Hubert Mackenzie Salmond, Fareham, and Anders Mathisen, London,

London, England England, assignors Graviner Manufacturin to g Company limited,

Application June 20, 1939, Serial No. 280,200 In Great Britain June 28, 1938 8 Claims.

acter the inertia element may take the form of a pendulum. ball element or mass, or it may be of any other convenient shape which is so arranged and disposed that when the device is subject to impact producing deceleration of specifled values, it efiects release 01' means for eflecting operation of the apparatus controlled.

The present invention more specifically relates to inertia operated devices comprising an inertia element or pendulum suspended from a universal character upon aircraft it is necessary to make periodic inspections and tests or the device and actuation and resetting of the device is desired without the necessity for applying impact to the device.

It is the object of the invention to provide a conveniently operable mechanism upon inertia operated devices for the purpose of actuating or tripping the device for test or inspection purposes, said mechanism preferably being also capable of facilitating resetting of the device after such intentional tripping.

According to this invention an inertia operated device comprising a suspended inertia element adapted for retaining a controlled member in a predetermined position and to release said memher when subjected to impact force or deceleration, is characterised by the provision of an auxiliary trip mechanism for actuating the inertia element to effect release oi the controlled member independently of an impact force or deceleration, said trip mechanism being operable to permit resetting of the inertia element into the position wherein it retains the controlled member.

'llms'wl'len an aircraft fitted with above dealso is standing or floating horizontally, and it is desired to test the device, the trip mechanism is operated manually, and thus the necescity for removing the cover 0! the device is avoided.

For resetting the device, means are provided which may be independent of but are preferably operable by the trip mechanism, and it is convenient to arrange that the latter mechanism itself can be moved subsequent to tripping of the inertia element to efiect positive resetting of the latter into its retaining position.

According to the invention where the inertia element is suspended by a universal joint the universal joint suspension mechanism of the device is so arranged that when an element, actuated externally from the casing of the device, is forced eccentrically against the universal joint mechanism, the inertia element is displaced to permit release of a part of the controlled mechanism.

By this means tests can be carried out and the device can normally be reset by moving the controlled mechanism into a position in which the inertia element re-engage said mechanism.

I! an aircraft is standing on the ground it is found that certain types of aircraft have the axis inclined to the horizontal to such an extent that it an inertia element controlled device has the controlled mechanism disengaged from the inertia element, tripping takes place automatically but resetting is not possible.

According to the invention the universal Joint suspension mechanism of the device is so arranged that when an element, actuated externally from the casing of the device, is forced concentrically against the universal Joint mechanism, the inertia element is brought into its normal vertical position so as to permit ngagement by the controlled mechanism to reset the Figure 6 shows the application of the control bar to reset the pendulum.

In the drawings the controlled member is an electric switch, but it will be understood that the trip and reset mechanism now to be described may be applied to any suitable controlled memher.

In the form of device illustrated, a pendulum i is suspended by a pivot pin 2 from a rotatably mounted spindle 3 so that the pendulum can swing in any direction.

In this embodiment the controlled member is an electric switch, comprising fixed contact springs 3 mounted in the casing 5 and actuated by a cam 5 which is fixed upon a shaft 7. Secured to the latter is a radial arm 8 which is controlled by a spring 9 so that it tends normally to swing anti-clockwise, see Figure 4. The outer end of the arm 8 carries a pin 10, which, in the retaining position shown in the drawings, the inertia element comprised in the pendulum 1 engages in a conical recess in the bottom of the pendulum, the efiect of suflicient impact force or deceleration being to cause the recess to jump the pin ii) whereby the arm 8 can turn anti-clockwise and open the switch contacts.

The upper end ll of the pendulum is made moderately fiat according to the present invention and a combined trip and reset device provided uponthe casing for the mechanism substantially as follows. Above the axis 2 oi. the

pivot pin of the pendulum l but eccentric with respect to the spindle axis 3 is produced a circular opening I2 in the casing 5 for the mechanism of the invention. In the opening is rotatably mounted a T shaped pendulum actuating element IS, the horizontal bar Hi of which is positioned in the opening i2, whereas the stem Isa projects through a flanged guide disc i5 secured to the casing 5. A projecting portion of the-stem is encircled by a spring It and an actuating knob ii is provided upon the end of the stem. The spring It is under compression and tends to retain the bar portion i l of the T shaped element in the opening of the case away from the pendulum and resting upon the guide disc l5 as shown in Figure The arrangements are such that when the bar i on the T shaped element is rotated to a position parallel with the axis oi the spindle 23 supporting the pendulum i, the bar, when pressed down against action of spring to, abuts eccentrically upon the upper end ll of the pendulum and tends to cause the pendulum to pivot away from its retaining position, i. e. the vertical. By applying suflicient downward force, the

bottom surface on the bar It (which as shown in Fig. 3 may be inclined to form a wedge shape) cams against the end H of the pendulum to swing the latter sufiilciently as shown in Fig. 5 to release the recess from the pin it whereby releasing or tripping of the switch mechanism for test purposes.

By rotating the T shaped element through a right angle, the bar it will project across the top of the pendulum end H, see Figure 4, and. if the bar is pressed against this end of the pendulum, a tendency will be produced to bring the pendulum into its retaining position. If the switch mechanism normally retained by the pendulum but now tripped is moved into appropriate position, engagement can be effected with the pendulum even if the axis of the aircraft and therefore of the device is inclined from the normal. For re-engaging the pin Id of the arm 8 with the pendulum, the shaft i projects through the casing and has provision, such as the handle It, for manually rotating the shaft 7.

In Fig. 6, the full line representation of pendulum i shows its tripped position when the airplane is grounded with tail on the ground. That is, when the airplane has its tail on the ground,

if pendulum I has been tripped, it will assume the position shown in full lines in Fig. 6, rather than the position shown in Fig, 5. Then even if lever arm 8 is rotated by shaft 1 from its tripped position shown in Fig. 5 to its set position shown in Fig. 6, pin 10 on arm 8 still will not engage the recess in the bottom of pendulum i while pendulum I is in the position shown in full lines in Fig. 6. If however bar [4, having been rotated as shown in Fig. 6 to lie across the top of pendulum end II, is now depressed, it will rotate pendulum i into the position shown in dotted lines in Fig. 6, in which position the pendulum recess is engageable with pin in. This makes possible test tripping and resetting with the plane on the ground as required in actual operation.

By providing telescoping rims on sleeves l9 and 26 respectively upon the guide disc l5 and the actuating knob H, the spring IE can be enclosed as shown. The combined trip andreset mechanism is capable of being mounted upon the casing of an existing device without requiring any modifications of the mechanism of the device, the guide disc l5 having set and trip" marking thereon as shown in Figure 2 to facilitate the manipulation of the device during testing.

The eccentricity of the T shaped element may be made so small that it is not readily possible to trip the device unless the pendulum engaging mechanism is moved out of engagement with the pendulum and by making suitable provision this is only possible by use of a special key, so that inadvertent or mischievous tripping of the device is not possible without application of excessive force.

For adjusting the tension of spring 9 controlling the shaft 7, the spring is anchored to a plate 2| which is mounted on the casing so as to be angularly adjustable about the axis of the shaft 7. Thus the plate 2| is provided with a plurality of holes 22 arranged in the are of a circle any one of which can be engaged with a fixed pin 23 by suitable adjustment of the plate.

Various modifications of the device described are within the spirit of the invention and separate devices for either tripping or resetting the pendulum may be utilised instead of a single device which is capable of effecting both operations. It is important, however, that no part projects into so close proximity to the universal joint mechanism that intereference with normal action of the pendulum mechanism might be caused.

Having thus fully described our invention, what we claim as new and desire to protect by Letters Patent is:

1. In an inertia operated device, an inertia element, a universal joint for suspending said inertia element, a controlled member, means actuatable by said inertia element adapted to normally retain said controlled member in a normal determined position and to release said controlled member from said normal position when said inertia element is subjected to impact or deceleration, a depressible test member for said inertia element, mounting means for mounting said test member depressibly and rotatably adjustable into two positions, said test member comprising a spring-controlled depressible stud element terminating in an enlarged head, said head being positioned to act eccentrically upon said universal joint and release said inertia element from normal position when said test member is depressed in its first said position and to act concentrically upon said universal joint and restore said tripped inertia element to normal position when said test member is depressed in its second said position.

2. An inertia operated device comprising a casing, an inertia element in the form of a pendulum suspended in the casing by a universal joint, a switch mechanism in said casing'including a switch control member normally engaging the pendulum so that the switch mechanism is retained in one position, said pendulum being adapted upon being subject to an impact force or deceleration to be released from the said member whereby the switch mechanism can move to another position, an auxiliary trip and reset element mounted on said casing so as to be adjustable into two positions, a trip position and a reset position, means whereby in the trip position, operation of the trip and reset element displaces the inertia element from engagement with the said switch control member to release the switch mechanism, and means by which in the reset position of the trip and reset member, operation of the latter restores the tripped inertia element to the retaining position.

3. An inertia operated device comprising a casing, an inertia element in the form of a pendulum suspended in the casing by a universal joint, a switch mechanism in said casing including a switch control member normally engaging the pendulum so that the switch mechanism is retained in one position said pendulum uponbeing subject to an impact force or deceleration being released from the said member whereby restore the same if tripped, when the trip and reset member is operated.

4. An inertia operated device comprising a casing, an inertia element in the form of a pendulum suspended in the casing by a universal joint, a switch mechanism in said casing including a switch control member normally engaging the pendulum so that the switch mechanism is retained in one position, said pendulum upon being subject to an impact force or deceleration being adapted to be released from the said member whereby the switch mechanism can move to another position, an auxiliary trip and reset member in the form of a spring controlled depressible stud mounted on the casing so as to be angularly adjustable into two positions, a trip position and a reset position, a head on said stud disposed above the universal joint suspension of the inertia element to engage the joint when the stud is depressed, said head having a trip surface and a reset surface, which upon depression of the stud engages the joint eccentrically or concentrically respectively to release or reset the inertia element depending upon the position of the stud.

5. In an inertia, operated device, an inertia element, means for suspending said inertia element displaceably under impact, a controlled member mounted for retention in a normal position thereof by locking engagement with said inertia element in normal position of said inertia element, and separate displaceably adjustable two-position combined tripping and resetting means mounted to engage said inertia element and adapted when actuated in its first position to displace said inertia element from position of locking engagement with said controlled member and in its second position to positively restore said inertia element to position of locking engagement with said controlled member.

6. In a safety switch, an inertia element having a mounting head, means for suspending said inertia element by its mounting head displaceably under impact, switch means adapted and mounted for retention in a normal position by locking engagement with said inertia element in normal position of said inertia element, and separate rotatably adjustable two-position combined tripping and resetting means comprising a terminal head and mounted linearly displaceably in substantially the direction of the vertical axis of said suspended inertia element in its normal position, said combined means being so mounted that in its first position when linearly displaced eccentrically it impinges on one side of said mounting head and displaces said inertia element from position of locking engagement with said switch means and in its second position when linearly displaced it applies restoring force to the entire said mounting head to thereby positively restore said inertia element to position of locking engagement with said controlled member.

'7. In a safety switch, a support, a first spindle rotatably mounted on said support, a second spindle mounted on said first spindle substantially at right angles thereto, a pendulum member suspended from said second spindle rotatably thereabout, switch means lockingly engageable with said pendulum member in a normal position thereof, and a combined tripping and resetting member longitudinally displaceably and rotatably mounted on said support and comprising a rod member mounted to extend longitudinally displaceably in the direction perpendicular to the plane containing the axes of said spindles but offset relative to the point of intersection of said axes, said combined member further comprising a head bar carried on its end adjacent said spindles and being so mounted that when said bar is rotated into a position parallel to said first spindle and depressed against said pendulum member it releases said pendulum member from normal locked position and that when said bar is rotated to a position substantially parallel to said second spindle and depressed against said pendulum member it restores said pendulum member to normal locking position.

8. In a safety switch, a support, a first spindle rotatably mounted on said support, a second spindle mounted on said first spindle substantially at right angles thereto, a pendulum member comprising a forked mounting portion which surrounds said second spindle for supporting said pendulum member rotatably from said second spindle, switch means lockingly engageable with said pendulum member in a normal position thereof, and a combined tripping and resetting member longitudinally displaceably and rotatably mounted on said support and comprising a rod member mounted to extend lormitudinally displaceably in the direction perpendicular to the plane containing the axes of said spindles but offset relative to the point of intersection of said axes to lie substantially in the axis of one fork of said pendulum member, said combined member further comprising a head bar carried 4 eeeeeae on its end adjacent said spindles. whereby when spindle and depressed against said pendulum said her is rotated into a position parallel to said member it" engages both forks thereof and refirst spindle and depressed against said pendulum stores said pendulum member to normal loci:- member it emgages one fork thereof and releases ing position.

said pendulum member from normal locked posl- 5 tion and further when said bar is rotated to e HUBERT MACKENZIE SOND. position substantially parallel to said second ANDERS MASEN. 

